Finally fixed the oil leak - Warning for those still using OEM drain plug/gasket.

[lupindub]

So after about a month of trying different things to stop the oil leak coming from the oil pan, I finally found the culprit. It was a combination of the paint from the OEM drain plug creating an uneven surface for the gasket to properly seal the oil AND the fact that the gasket Subaru/Toyota supplies does not sit flush with the plug like some aftermarket drain plugs. For whatever reason Subaru decided to put the gasket + drain plug on the drain pan BEFORE painting it which caused this uneven surface.

Here are the pics showing the problem:

Without the gasket - Notice how the edges are un-evenly painted


With the gasket - definitely not flush


Compared to Fumoto Valve (Notice how the gasket sits flush WITH the plug)


Solution: Switch to an aftermarket plug (Fumoto Valve).

One thing I should mention is that it is such a small oil leak that you will only lose a couple of drops a day. One way you can tell is if you have little oil droplets under the area you park. If you park outside you will probably not notice even if you do park in the same spot due to rain/nature washing away any evidence before collecting too much (mind you it took me 6 months to finally notice and I park in a garage).

So overall if you don't care about the tiny mess this will cause, I say leave it as it is since this won't cause any major issues if you are properly changing your oil every 7.5 months/7500 miles. Even whilst my car was leaking oil, I never had to top it off even once. YMMV.

[Cole]

Well, given that it's a crush washer, it should deform to whatever it's mating with and still not cause a leak.

[lupindub]

Originally Posted by Cole

Well, given that it's a crush washer, it should deform to whatever it's mating with and still not cause a leak.

Only one side "crushes". The mating surface of the bottom of the crusher does not crush. Theoretically this would be fine since the drain plug should be FLAT and not have paint on it (or lack of) and mate well with the flat part of the crusher.

[Ultramaroon]

It's cheaper to paint the pan with the drain plug already installed than it is to mask it, paint it, remove masking, install drain plug.

I can see where some plugs might have more paint buildup than others. Just the luck of the draw. I think I went at mine with some acetone and a rag. Don't remember exactly.

Yes, both sides of the gasket deform. Orientation doesn't matter. Be careful not to overtorque.

[mav1178]

I think this is an assembly line manufacturing issue.



This is a cropped picture of the Blitz oil pan, a modified OEM pan w/ the turbo oil drain tube.

There are no issues with paint on the bolt and washer... my original bolt however, did not look the same when I took it off my car:
http://www.ft86club.com/forums/showthread.php?t=54142

The Blitz oil pan was purchased as an individual unit originally from Toyota/Subaru, and the paint is much cleaner around the bolt.

-alex

[lupindub]

Originally Posted by Ultramaroon

It's cheaper to paint the pan with the drain plug already installed than it is to mask it, paint it, remove masking, install drain plug.

I can see where some plugs might have more paint buildup than others. Just the luck of the draw. I think I went at mine with some acetone and a rag. Don't remember exactly.

Yes, both sides of the gasket deform. Orientation doesn't matter. Be careful not to overtorque.

Not to be pedantic but the orientation does matter... Flat side should be facing toward the plug and the rounded part towards the oil pan. I even asked the dealership about this the other day.

[Ultramaroon]

Originally Posted by lupindub

Not to be pedantic but the orientation does matter... Flat side should be facing toward the plug and the rounded part towards the oil pan. I even asked the dealership about this the other day.

If it mattered, the service manual would specify. No biggie, tho.

[roddy]

I didn't really like the loose fit either. The next size down is like a standard Honda drain plug (14MM?), and is just a bit too tight. I've been using the OEM size replacements for about 20 oil changes (95,000km, changed every 5,000). The fit is a little wonky, but the seal has been good. I only had one very minor leak, and that was my own fault.


I much prefer the thick aluminum style drain plug gaskets (washers), but hesitate to use them. For anyone who does their own oil changes, you've probably noticed how short our drain plugs are...after breaking it loose, it seems like it only takes a couple of turns, and it shoots out of your fingers and into the bottom of the drain pan. Using the thicker style plug gasket would effectively shorten the depth of the plug that much more. I'm probably over thinking that a little bit...

[Cole]

Originally Posted by roddy

I didn't really like the loose fit either. The next size down is like a standard Honda drain plug (14MM?), and is just a bit too tight. I've been using the OEM size replacements for about 20 oil changes (95,000km, changed every 5,000). The fit is a little wonky, but the seal has been good. I only had one very minor leak, and that was my own fault.


I much prefer the thick aluminum style drain plug gaskets (washers), but hesitate to use them. For anyone who does their own oil changes, you've probably noticed how short our drain plugs are...after breaking it loose, it seems like it only takes a couple of turns, and it shoots out of your fingers and into the bottom of the drain pan. Using the thicker style plug gasket would effectively shorten the depth of the plug that much more. I'm probably over thinking that a little bit...

I haven't changed the oil yet myself (only had 3 so far), still have a bunch of free ones, and apart from my first change, where I found a bunch of oil pooled in the skid plate from what I can only assume is a tech's incompetence. I have not noticed any leaks with the factory drain plug/washer combo. Probably will not deviate from it once I start doing them on my own.

[humfrz]

Originally Posted by lupindub

Not to be pedantic but the orientation does matter... Flat side should be facing toward the plug and the rounded part towards the oil pan. I even asked the dealership about this the other day.

That makes since ....... the flat side next to the part that is turning (the drain plug) so it would make a better "squish".

A good squish is important .......


humfrz

[babydriver]

Originally Posted by lupindub

Not to be pedantic but the orientation does matter... Flat side should be facing toward the plug and the rounded part towards the oil pan. I even asked the dealership about this the other day.

Strangely enough, I had the same problem when I switched to the Greddy drain plug very recently. With the flat side facing towards the oil pan, it leaked a little. With the flat side facing towards the plug itself, no leak. I suspect that the rounded side not only squashes but inserts slightly into the drain hole and is therefore deformed around the edges of the hole, providing a little extra bit of seal. Just a guess, I do know that the orientation seems to matter.

[lupindub]

Originally Posted by Cole

I haven't changed the oil yet myself (only had 3 so far), still have a bunch of free ones, and apart from my first change, where I found a bunch of oil pooled in the skid plate from what I can only assume is a tech's incompetence. I have not noticed any leaks with the factory drain plug/washer combo. Probably will not deviate from it once I start doing them on my own.

I had oil pool up in my skid plate as well (part circled in red) from the slow oil leak I had going on.